(F-217) Dose-Dependent Effect of Extracellular Matrix Nanoparticles on Neutrophilic Response to Lipopolysaccharide- Induced Lung Injury

Introduction:: Acute respiratory distress syndrome (ARDS) is a severe form of lung injury characterized by pulmonary edema, rupture of the alveolar-capillary barrier, and a severe neutrophilic immune response. There is no cure for ARDS and the current standard of care is providing respiratory support through mechanical ventilation, inhaled therapies such as bronchodilators and vasodilators, and other methods to treat symptoms of respiratory failure. This study utilizes a novel, electrically charged nanoparticle fabricated from xenographic, organ-specific extracellular matrix (ECM). ECM has been explored for treatment of lung disease through inhalation of solubilized suspension, micro-sized inhaled particles, and more; however, organ-specific solubilized inhaled nanoparticles are a novel treatment. We hypothesize that the inhaled nanoparticles will improve the neutrophilic immune response to LPS injury.


Materials and Methods:: Cryomilled, decellularized porcine lung tissue was digested and electrosprayed to form ECM nanoparticles as previously described (Link 2018). The size and zeta-potential of the particles were measured using a Malvern Zetasizer ZN90. Scanning electron microscope (SEM) images were obtained. To test efficacy of the nanoparticles in vivo, 12-20 week old C57/bl6 mice were anesthetized and orotracheally intubated. 50 uL of 0.9% saline or lipopolysaccharide (LPS) (2 mg/kg) were administered. 5 minutes later, 50 uL of 0.9% saline or ECM nanoparticles at assigned dosage (0.0625, 0.125, 0.25 mg/mL) were administered and the mice were allowed to recover. 24 hours after LPS dosing and treatment, the mice were sacrificed and samples were collected. Bronchoalveolar lavage (BAL) fluid was analyzed for protein content and inflammatory cell infiltration. Lung histology was performed to quantify alveolar barrier damage.


Results, Conclusions, and Discussions:: Results: LPS injury induces ~90% neutrophil presence in BAL fluid. In male mice, ECM nanoparticles at a dose of 0.0625 mg/mL (0.5x) significantly decrease neutrophil percentage in BAL fluid. In females, a similar trend in neutrophil reduction was observed for 0.125 mg/mL (1x) nanoparticles. There is no significant difference between positive controls and 0.25 mg/mL (2x) nanoparticle dose. Additional study findings include a significant sex difference between male and female ECM treatment groups in total protein and total cells in BAL fluid, improvements in inflammation in lung histology, and decreases in inflammatory cytokines with treatment.



Conclusions: It is known that male mice show a more exaggerated immune response to LPS injury than female mice, but sex differences in response to ECM treatment have not been explored. In this study, ECM nanoparticles decrease the neutrophilic response to LPS-induced lung injury and improve the immune response. There is a sex difference in the most effective dose, with the male mice performing best with a lower dose of nanoparticles than female mice. Future studies will include administration of a lower dose to female mice, increasing n-values, and further analyzing protein expression and cytology in BAL fluid.


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